A conventional clip for fastening sheets of paper together is generally made by bending an iron wire into pairs of legs and bends around a circle. FIG. 1 shows a clip of this type. This structure of clip is suitable for fastening few sheets of paper. When several sheets of paper are fastened together, as shown in FIGS. 2, 3, and 4, either bend of the clip may project, causing the sheets of paper to escape from the clip, or the clip may be forced to deform, causing a damage to the sheets of paper.